The present invention relates to a technology for detecting, checking, correcting, and processing a specific pattern of a mask used when semiconductor products, display devices for plasma display panels or liquid crystal display panels or a magnetic devices are produced.
In recent years, as a semiconductor product and the like are reduced in size and increased in packing density, a mask pattern is remarkably increased in packing density and reduced in size, and high precision for a pattern forming procedure and high quality of the pattern are required. Although the amount of mask pattern is increased, it is required to swiftly carry out the inspection for checking precision of the mask pattern and feedback of failure mask pattern so as to shorten the developing time period of the semiconductor product or various devices. It is also necessary to effectively and precisely correct a mask pattern or process an LSI pattern formed on a wafer. Therefore, it is necessary to precisely check a target pattern in the mask pattern to be checked, corrected or processed.
As a conventional checking method of a mask pattern, there is a method in which a pattern having the same size as that of a pattern whose device characteristics must be ensure is disposed on a position where the pattern can easily be detected based on an alignment reference position out of device forming region, thereby detecting the pattern. If patterns become smaller as in recent years, deformation is generated in the pattern due to proximity effect or difference between coarse portion and fine portion (coarse-and-fine difference, hereinafter). According to this conventional method, however, it is not possible to check the pattern while taking influence on a device function or characteristics caused by the deformation of pattern into account.
Thereupon, in recent years, there is employed a method in which a pattern having great influence on its function or characteristics among patterns in the device forming region is designated as a pattern to be checked (target pattern, hereinafter), and the target pattern is checked. According to this checking method, in order to detect the target pattern, the pattern is automatically detected by visually confirming the pattern by a checking operator or moving a stage or a detecting optical system from an alignment (positioning) reference position out of the device forming region to coordinates of the target pattern. If the moving precision of the stage or the detecting optical system is not sufficient in this automatic detecting operation, it is necessary to visually confirm its state after the automatic detecting operation. There is also a method for detecting the target pattern by carrying out a data comparison collation check (Die TO Data check) while scanning the entire surface of the device forming region.
According to the method for checking the target pattern in the device forming region, however, since a pattern whose function or characteristics are largely influenced is set as the target pattern, the target pattern is not always disposed on an convenient position when the target pattern is checked. In other words, there is inconvenience that the target pattern is disposed on a position where it is difficult to detect the pattern in some cases. Further, when the target pattern is visually confirmed, if devices further become finer and denser and it is necessary to set a large number of, e.g., several hundred target patterns, there is a problem that the operational efficiency is inferior.
When the target pattern is automatically detected, with enlargement of the effective resolution region of recent pattern light-exposure device and with higher function of device, the device forming region is further increased. Therefore, there is a problem that the moving amount of the stage or detection optical system is increased and the moving error is also increased. In an existing checking device, for example, when the moving amount of the stage is about 40 mm, precision of a device using a stepping motor is about xc2x15 xcexcm, and precision of a device using an encoder is about xc2x11 xcexcm, and precision of a device using laser interferometer is about xc2x10.5 xcexcm. The precision of any of these devices is insufficient for producing a device of 0.25 xcexcm rule which becomes popular in recent years.
A stage system having extremely high precision used for an EB light-exposure device or the like may be used, but a new problem that equipment cost of the checking device is largely increased, and the device is increased in size is created. When the data comparison collation check is carried out while scanning the entire surface of the device forming region, since the pattern is checked including its shape, there are a problem that precision is inferior to measuring precision of a size check and a problem that several tens of minutes to several hours are taken for one plate such as a mask or a reticle and the checking time is increased.
A pattern suitable for alignment of the checking device can previously be provided in the vicinity of a target pattern, but this necessitates inserting a pattern which has nothing to do with function or characteristics of the device into the device forming region and thus, this is not preferable for satisfying the enhancement of chip yield by enhancing the function of the device or reducing the chip area.
It is an object of the invention to provide a method of and device for detecting pattern, in which alignment reference coordinates are set in a region near a target pattern in a device forming region, and the target pattern can swiftly and automatically be detected with high precision based on the alignment reference coordinates. It is another object of the invention to provide a method of and device for checking the target pattern detected by the pattern detecting method, and a method of and device for correcting or processing the pattern.
It is another object of this invention to provide a computer program that contains instructions which when executed on a computer realizes the method according to the present invention on the computer.
The pattern detecting method according to one aspect of the present invention comprises selecting, from a region near a target pattern to be processed in a device forming region having a group of patterns corresponding to a device to be produced, as an alignment pattern in a device forming region, patterns whose barycenter positions (i.e. center of gravity) in a first direction are not changed even if adjacent patterns approach and are deformed or patterns are deformed by coarse portion and fine portion thereof at the time of pattern forming, and setting a barycenter position of the alignment pattern in the first direction as alignment reference coordinates, and detecting the target pattern based on the alignment reference coordinates.
The pattern detecting method according to another aspect of the present invention comprises selecting, from a group of device patterns included in a region near a target pattern to be produced, as an alignment pattern in a device forming region, patterns whose barycenter positions in first direction (for example, X direction or Y direction) and second direction (for example, Y direction or X direction) are not changed even if adjacent patterns approach and are deformed or patterns are deformed by coarse portion and fine portion thereof at the time of pattern forming, and setting a barycenter position of the alignment pattern in the first and second directions as alignment reference coordinates, and detecting the target pattern based on the alignment reference coordinates.
The method of and device for checking the target pattern according to still another aspect of the present invention comprises checking the target pattern detected by the pattern detecting method.
The method of and device for correcting or processing the pattern according to still another aspect of the present invention comprises correcting or processing the target pattern detected by the pattern detecting method.
The computer programs according to still another aspect of the present invention stores instructions which when executed realizes the method according to the present invention on a computer.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.